High-frequency tube structure



@CL 12, 1948 w. w. HANSEN ET AL. 2,450,893

HIGH-FREQUENCY TUBE STRUCTURE Original Filed May 17, 1941 2 Sheets-Sheet l INVENTORS, WILLIAM -W. HANSEN, E.

JOHN R WOODYARD;

R ATTORNEY Oct. l2, 1948. w, w, HANSEN ETAL 2,450,893

HIGH-FREQUENCY TUBE STRUCTURE 2 Sheets-Sheet 2 Original Filed May 17, 1941 INVENTORS.

'WILLIAM w HANSEN,& Jol-1N R WOODYARD;

THEIR ATTORNEY ber 49 near the fastened end of this member, and at the other end in its screw 39.

Fig. 2 shows plate 29 with rods 4I and 43 in their normal operating position. These rods are held in position in the actual device by the opposition to deformation of the resonating chamber 1 created largely by atmospheric pressure acting on the evacuated casing 33, as described below. While the cantilever tuning means has been shown as applied only to the first resonating chamber, it is obvious that it could equally well be applied to any of the others.

Resonating chambers 9 and II have their rigid walls I5, I1 connected together as by peripheral connection member 6I, which carries a flange 53 similar to flange 35. Flange 53 carries screws 65 similar to screws 39, which transmit thrust through thrust rods 61 to plate 29. Resonator II has its flexible wall centrally apertured and carries a tube 1I terminating in outer cooling fins 13. Mounted on this tube 1I is another thrust plate 15 carrying thrust screws 11 bearing against thrust rods 19 which in turn bear against flange 63, the usual lock nuts 8| being provided.

Each of the resonating chambers 1, 9, I I has provided means for supplying or abstracting high frequency energy in the form of concentric line terminal posts 83 whose inner conductors terminate in coupling or pick-up loops 85.

In operation, electrons emitted by the cathode 2 form a beam which may be modulated by supplying suitable modulating potentials or signals to grid 5. The electrons are accelerated by the potential diierence between cathode 2, usually maintained at a high negative potential, and rigid wall I3, which acts as an accelerating electrode and is usually grounded. As is well known, the passing of the beam through the rst resonating chamber 1, known as the buncher, effects recurrent changes in velocity of the electrons of the beam. Passage of electrons through the drift tube, 25 permits the electrons to bunch, and to give up their energy upon passage through the second resonator 9, known as the catchen Output energy can be obtained from the resonator 9.

However, in order to prevent the abstraction of energy from affecting the frequency characteristics of resonator 9 and of resonator 1, which may, in some applications of the device, be coupled to resonator 9, the electron beam, now bunchedf is allowed to pass through the further resonator I I, and output energy is obtained from this resonator, which cannot reect back into the other resonators 1 and 9 to change their frequency characteristics since it is coupled to the other resonators only by the electron beam. The novel tube of this invention thereby includes a buier stage or resonator as well as the "buncher and catcher stages or resonators. The grids carried by walls I5 and I1 are spaced apart a distance much less than the distance between the grids on opposite ends of tube '25, but are spaced far enough to insure against coupling of the field of resonator II back to the field of resonator 9. At the same time, as illustrated in Fig. 1, the grids carried by walls I5 and I1 are suiciently close together that both resonators 9 and II extract energy from the bunched electron beam within a relatively small region where the condition of electron bunching in the electron beam varies but little due to the small transit time.

As is well known, the frequency of operation of such devices as the present depends on the size and shape of the resonating chambers. The

present invention provides means for adjusting the frequency of each of the resonators. Thus, it

is clear that turning screws 11 will create a thrust between plate 15 and iiange 63, which will be transmitted to the rigid wall I1 and the flexible wall 23 of resonator Il to create relative thrust therebetween. This thrust is opposed by the action of atmospheric pressure on the evacuated chamber, which tends to collapse the flexible wall. This adjustment of screws 11 therefore causes deformation of the flexible wall 23, thereby changing the resonating frequency of this resonating chamber. Once adjusted, the frequency may be maintained by use of the lock nuts 8i to malntain screws 11 in desired position.

Turning screws 65 will in like manner create relative thrust between the rigid and exible walls of resonator 9 and cause tuning of this resonator. It will be noted that this tuning cannot affect the tuning of resonator II, since no thrust is created between the rigid and flexible walls of that resonator by turning screws 65. At most, a slight motion of the whole resonator II occurs, due to deformation of iieXible wall 2| of resonator 9.

In the same manner, the frequency of resonator 1 can be adjusted by screws 39. Here again, no eifect is produced on either of the other resonators. It is obvious that the tuning of each of the resonators is independent of any other, and the resonators may be adjusted in any desired order.

In the case of resonator 1 there is further provided the novel fine cantilever adjustment for tuning above described. It will be seen that turning micrometer handle 51 will create a. thrust on resilient cantilever 49 through ball 59. This thrust is transmitted to rod 4I by the cantilever action of member 49 and thence to resonator chamber 1. A dual refinement of tuning is obtained by this means. First, there is the refinement by use of a micrometer screw instead of the ordinary screws 39. There is a second reiinement in tuning by use of the cantilever arrangement, even over an ordinary rigid lever arrangement. If an ordinary lever were used, pivoted at screws 41, the motion of rod 4I would be reduced relative to that of micrometer rod 5I by a factor which is proportional to the ratio of their relative distances from the pivot. The novel method -here used obtains a further refinement over such a pivoted lever arrangement, since the reduction in deflection of rod 4I, using the cantilever arrangement and neglecting the opposing force created by rod 4I, is by a factor roughly proportional to the square of the ratio of the relative distances, since the cantilever assumes a roughly parabolic shape. Furthermore, the effect of the opposition of rod 4I to being moved by the application of force to the end of the cantilever 49 is to further reduce 4the relative motion, and to eiect further refinement of tuning. From another point of view, this results in further curvature of the cantilever spring 49,

making the displacement of rod 4I proportional to the applied motion by a factor which is inversely proportional to even higher powers of the distancev ratio than the second power. It will be seen thus that extremely ne and sensitive tuning adjustments can be made, which is essential for successful operation, especially in small tubes operating at high frequency, where the slightest change in size and shape produces extremely large changes in resonating frequency.

Fig. 3 shows an arrangement in which resonais coupled back to resonator 1.` as by .transmission linel H2, thereby `causing tube I yto 'gen- `mteosci1lations The output of tube l is taken l'from buffer .resonator il by means of transmission line U3 to preserve stability of oscillation, and is connected, to any suitable load, such. as anantenna.

.Y As many changes could be made the above -constru-cions and many apparently widely differ- .ent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above ldescription or shown in the accompanying drawings shall be interpreted as illustrative and not infalimiting sense.

What is claimed is:

Jl; Anelectric discharge tube comprising means crgenerating a stream of electrons, a first aper- `turen hollow resonator axially positioned with respect to the path .of said ,stream and adapted yto velocity modulate said electron stream, a. second hollow apertured resonator also axially posi- `#tionen with respect to said path, and adapted .to be energized by said stream, a drift tube connecting and spacing said first and second resonators to permit electrons in electron flow therelbetween andro permit said velocity modulated stream to Abecome hunched, a third hollow apertured vresonator .axially placed with respect t0 said path close to said second resonator, said second andthird resonators being coupled to said electron stream sufficiently far apart to prevent couplingof the .third resonator field back to the second resonator field, but sufficiently close that said electron streamuundergoes little change in bunching while passing'between said second and resonators, and means for abstracting .high frequency energy from said third resonator whereby the abstraction of high frequency energy from said electron discharge tube will not affect the resonating characteristics of said second or Afirst resonators.

2. An electron discharge tube comprising an :electron gun forigenerating a stream of electrons, @ahollow aperturcd resonator positioned axially .with respect to the path of said stream and havving a rigid wall facing said gun anda flexible Vwall opposite said rigid wall, an intruding p0rtion mounted on said flexible wall and extendtoward said rigid wall, and having a hanged *portion of extensive area adjacent and parallel to said rigid wall, a second hollow apertured resy onatorl axially positioned with respect to said ,path and yhaving a flexible wall facing said gun and a rigid wall opposite said last-named flexihle wall, a drift tube laxially positioned with respect 'to said path and connecting said iiexible mails together, a plate rigidly mounted transversely -on said drift tube, a cantilever spring member rigidly fastened at one point to said plate, .a micrometer screw adjuster having a iixed portion fastened to said plate and a movable porf tion to-move the free end of said spring perpendicular to -said plate, a ange rigidly connected 'to said first rigid wall, anda thrust rod positioned 'between said flange and a point on said spring between the iixed point. and the end driven by said micrometer screw to transmit thrust from said spring to said flange whereby said iirst chamber may be tuned by change in its size and shape upon rotation of said micrometer screw.

3. An electron discharge device as in claim' 2, in which said flange carries an adustable screw and in which a second thrust rod is positioned between said adustable screw and said plate wherer6 'by tuning of said erst resonance chamber may be eiectedby rotation of said screw.

4. An electron discharge tube as in claim 2 further comprising a flanged member connected to the rigid wall of said second resomitor,y an adjustable screw carried by said flanged member and a second thrust rod placed between said screw and said plate, whereby coarse tuning of said second resonating chamber may be .eicted by rotation of said screw. Y

5. A hollowresonator for use in electron discharge tubes comprisingV a front wall and a rear wall, both walls having aligned apertures adapted togpermt the passage of lan electron beam .therethroughan inwardlyextending portion connected to one of vsaid walls and axially aligned withsaid apertures, said portion terminating in aflange extending adjacent and substantiallyparaliel to the other of said walls, and having an opening adjacent to the aperture in saidother wall, said .opening .and said `last-named aperture containing `grids for controlling said electron beam. 6.. A hollow resonator foruse in electron discharge tubes, comprising a. front wall and a rear wall, both walls having aligned apertures vacbspted to permit the passage of an electron beam therethrough, and an inwardly extending portion connectedto one of said walls and. axially aligned with said apertures, said portion terminating in a iange extendingv adjacent and substantially parallel to the other of said walls and having .an opening adjacent to the aperture in said other wall. '7. A resonator for use in electron. .discharge tubes, comprising a casing having a front wall and a rear wall, both `ot' said Walls aligned apertures adapted to permit passage of an electron bam therethrough, an inwardly extending portion connected to one of said walls and axially aligned to. said apertures, and cooperating surface means on said portion Vand the other .of

said walls for providing increased capacitance be- `tween said portion and said other wall, whereby .for a given operating frequency the effective size of said resonator may be reduced. I

8. A hollow resonator for use in electron discharge tubes, comprising a casing having aligned apertures adapted to permit the passage of an electron `beam therethrough, one wall of said casing lhaving a reentrant portion, and cooperating means on said reentrant portion and the opposite wall for providing increased capacitance between said reentrant portion and said opposite vwall of said resonator, whereby for a given operating frequency the effective size of said resonator `may be reduced.

9; A tunable high frequency device, comprising a hollow resonator having rigid and flexible Wall'portions, a flexible cantilever member having one end fixed to one of said portions, a thrust memberv interposed between said cantilever member andthe other of said portions, and means operatively coupled to said cantilever member for flexing said cantilever member to thereby relatively 'displace said wall portions and vary the tuning of said resonator.

l0. A tuning control mechanism for a high frequency electron discharge tube having a cavity resonator with a flexible wall portion, said mechanism comprising a tuning control member, a

bendable lever adapted to be anchored at one end to said tube and operatively connected to said.

7 saidflexiblewall portion,I whereby deflection of said flexible wall may be controlled'by said 'control member.

1l. High frequency apparatus comprising means for producing a grouped electron stream, a hollow resonator along the path of said stream for extracting energy therefrom, means providing a relatively small space through which said electron stream passes beyond said first resonator, a further hollowresonator along the path :of said electron stream beyond said space, said space being suinciently large to prevent coupling ofthe eld of said further resonator back to the rst resonator field, and being suii'ciently small vto enable said further resonator to couple with the electron stream before it has time to undergo an appreciable change in its conditon of bunching beyond said rst resonator, and means coupled to said further resonator for extracting energy therefrom.

12. High frequency electron discharge apparatus comprising means'for producing an electron stream, three hollow resonators spaced insuccession along the path of said stream in energy exchanging relation therewith, means providing an electron bunching space between the rst two resonators to permit electron bunching in the stream between said rst two resonators, and means providing an electron Ybeam transit space between the second and third resonators which isV .much shorter than said electron bunching space, so that said second and third resonators are coupled to said electron stream in appreciably closer succession than are said first and second resonators.

13. High frequency apparatus comprising a hollow resonator device having two spaced parts which are relatively movable for varying the frequency of said resonator, and means for effecting relative movement of said parts comprising a ,resilient lever lsecured to one of said parts, thrust means interposed between said resilient lever and the other of said parts, and means coupled to said lever for controllably flexing said resilient lever.

14. The apparatus dened in claim 13, wherein said resilient lever is a spring leaf anchored at one end to said one part, and said means for iiexing the lever comprises a micrometer assembly Vmounted on one of said parts.

l5. High frequency apparatus comprising a .hollowresonator having a first end wall formed with an electron permeable region and an opposed flexible end wall, a hollow tubular member mounted on said flexible wall in alignment with said region, said tubular member extending into said resonator to a point adjacent said region and extending outwardly beyond said exible wall, and an electron collector electrode on said tubular member externally of said resonator.

16. High frequency apparatus comprising means for producing an electron stream, and three hollow resonators spaced in succession along the path of said stream, said path between the rstand second of said resonators being several times as long as the path between the Second and third of said resonators..

17. Apparatus as in claim 16, further including `8 means coupling said ffirst an'd second resonators together, and means coupled to said third resonator for extracting high frequency energy therefrom, whereby variations in said energy extraction do not affect the operation of said coupled first and second resonators.

18. Apparatus as in claim 16, further including a pair of independent outputs and means coupling one of said outputs to said second resonator and means coupling the'other of said outputs Ato said third resonator.

`19. High frequency apparatus comprising a hollow resonator having a pair of end walls, one of said end walls being formed with an electronpermeable region, a hollow tubular member mounted on the other of said wallsin alignment with said region, said tubular member extending into said resonator to a point adjacent to said region and extending outwardly beyond said other wall, and an electron collector electrode conductively connected to and closing said tubular member externally .of said resonator.

20. High frequency apparatus comprising a hollow resonator having a pair of opposed walls, one of said walls being formed with an electronpermeable region, a hollow tubular member mounted on the .other of said walls in alignment with said region, said tubular member extending outwardly of said resonator away from said other wall, and an electron collector electrode conductively connected to and closing said tubular member outside said resonator.

WILLIAM W. HANSEN. JOHN R. WOODYARD.

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